Thread locking and releasing device for sewing-machines.



J. D. RANDALL.

1,237,555., v PatentedAug. 21,1917.

I I ,A. M i v w Fig. 3.

JAMEsD. RANDALL, or CINCINNATI, oIIIo, ASSIGNOB. TO THE ;r. n. RANDALL co1vI- IPANY, OF CINCINNATI, OHIO, A CORPORATION OF OHIO.

THREAD LOCKING AND RELEASING DEVICE non SEWING-MACHINES.

Specification of Letters Patent. Patented A g; 21" 191% Application filed December 16, 1915. Serial No. 67,155.

1T0 all whom it may concern:

Beit known that I, JAMns D. RAN ALL, a citizen of the United States of America, and resident of Cincinnati, county of Hamilton, State of Ohio, have invented certain new and useful Improvements in Thread 1 Locking and Releasing Devices for Sewmg- Machines, of which the following is a specification.

This invention relates to-improvements 1n 1 thread tension devices for sewing machines of the type disclosed in United States Letters Patent No. 388,752, issued to George Amborn on August 28, 1888. In sewing machines of the type disclosed in said Letters Patent, the thread is locked by the front and rear thread-brakes 4 and 5, while the take-up 22 and 23 is operating,

and while the thread is being drawn forward by the needle, said thread brakes are open. When the operator desires to drop a stitch, he stops the machine and draws enough thread forward to enable him to ordinary operation of drop stitching.

A further object of my thread releasing device is to place the device under control of the operator without having to take the operators attention and hands from the work being done.

These and other objects are attained in the device described in the following specification and illustrated in the accompanying drawings in which;

Figure 1 is a fragmental elevation of the upper portion of a sewing machine constructed for sewing heavy materials such as leather, having a tension releasing device embodying my invention attached thereto.

Fig. 2 is a fragmental perspective v ew of a section of belting having a portion thereof drop stitched, to illustrate the work done by my improved construction.

Fig. 3 is a view similar to that of Flg.

I 2, but illustrating the work ordinarily done in drop stitching operations.

In sewing machines of the type disclosed In the above mentioned patent, employed in the stitchingv of harness and similar heavy materials, two thread locking devices 4 and 5 a re employed, each of these devices conslst ng of frontand rear thread brakes 6 and 7 plvotally mounted on pins 8 and 9 extending fromfa bracket 10 mounted on the top.

of the frame 11 of the machine, and brake blocks12 and13 against which the brakes 6 and 7 bear. On the opposite sides of the brakes,arms.14and 15 are formed, these arms being under tension by means of coiled springs 16 and 17 adapted to retain the brakes 6 and 7 in engagement with the blocks 12 and 13. In order to prevent displacement of the thread from the blocks and brakes, a guide 19 is provided between the blocks and secured ,to the bracket 10, while on the opposite sides of the blocks and brakes, the thread is passed through eyelets 20 and 21 formed as integral parts of the arms 14 and 15 of the brakes 6 and 7 The usual take-up, consisting of the reciprocating pulleys 22. and 23, is employed for taklng up the thread carried forward by the needle.

In order to release the clamping action of the" brakes 6 and? upon the blocks 12 and 13, I employ the following described mechanism. Pivotally mounted at a point 25 on a bracket 26 mounted on the frame 11, is a lever 27 which in said Amborn Patent No. 388,752, is adapted to raise the presser foot. I provide the forward end of this lever with a pin 28 which operates in a slot 29 formed in the bracket 10. This pin engages a cam 30 and is adapted to cause rotation of the cam upon its pivot pin 31, by riding over the cam surface 32 when the lever 27 is 0perated to move the pin upwardly through the slot 29. This oscillatory movement of the cam is communicated to the arms 14 and 15 of the brakes 6 and 7 to lift the brakes from the blocks 12 and 13 and thereby release the thread, the means for communicating this motion tothe arm 14 consisting of a stud 33 reciprocally mounted in bearing lugs 34 mounted on the bracket 10, and which engages the under side of the arm 14 and the upper side of a finger 35 of the cam 30. The arm 15 of the brake 7 receives motion from the cam 30 by means of a lever 36 pivotally mounted on a pin 37 in the bracket 10, the forward end of the lever having a 'tooth'38 engaging a recess 39 of the cam 30 for operation therewith. The rearwardly 5 extending arm 40of-the lever-36 engages the under side of the arm 15 of the brake 7.

Thus when the pin. 28 .is :moved .upwardly in the slot 29 to cause the cam 30 to rotate upon the pin 31, the --stud 83 and'consequently the arm 14 of the brake 6, are raised, asarealsothe arm 40 ofthe lever 36 and the arm 15 of *the brake 7 beoause'of the engagement of the tooth 3-8 and the recess formed inthe cam30. This'oper 15; ation "causes simultaneous releasing 'of the thread at dooth thread brakes and permits of its being drawn so *freely from its source of supply and iromthe needle at the foot "of "the machine, that the shifting "of the workto whihthe thread is attached pulls "out the thread "as the work is shifted to the point at which the stitching is again startedp @peration of the lever-27 which earries the pin '28 is caused by a rod 41 whichisconnectedwith the rearend 'of'the lever and which is operated by -a foot treadle convenient 'to the operator. The lever 27 is maintained in its normal position with "the pin 28 at the bottom of the 30 'slot *29, by means 'of-"a coiled=springt2 secured-thereto at oneen'dandto an arm 4:3

'of thebrack-et 26 atits opposite end.

Having flthus described my invention, what I claim is;

1. A thread releasing device for sewing -m-achine's, comprising :a "block, a brake adapted to 'clamp a thread between it and the block, an "arm formed on the brake adapted to be moved to lift the brake from '40 the block to release the thread, a spring 'attached to the arm normally holding the brake in yielding-engagement with "the block to clamp the thread between the brake nected therewith, and a lever operatively connected with the cam for causing the cam to lift the brake to release the thread.

.2. Ina thread releasing device for sewing machines, the combination of a block,

-a brake 'adaptedto clamp a thread between it and the block, an arm formed on the brake and adapted to be moved to lift the tioned brake and adapted to clamp "the.

thread "passing *from the first mentioned brake -and bloek, "between it 'and the second mentioned bloclg'an' arm 'formed'on the second i'nentioned brake and "adapted to he moved to lift -the=bra-ke from the block'to mounted adjacent to the brakes and 1 open atively connected therewith, "and a lever operatively connected with 'the cam for causing simultaneous releasing movement of thebrakes when,- the lever ISOPQIZLDQd.

,. and the block,- a cam pivotallymounted ad- I fjacent .to ithe brake .and operatively con- In testimony whereof, I have hereunto subscribed -m y*-n ame this 13th day of De JAMES B. "RANDALL.

WVitnesses "WABKER 'F. MURRAY,

. THORNTON BoeER'r.

coplem of this patent may 'be obtaine'd' for five cents 362K711, :byzaddressi'ng 5 the ffiommis'sioner of Patents,

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